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Oral food challenge outcomes differ among individual tree nuts

Published: June 15, 2021

Tree nuts are common food allergens and patients who have a reaction or possible allergy to one nut will often avoid all other tree nuts. Little is known regarding allergenicity differences between individual tree nuts. While oral food challenges (OFCs) remain the gold standard for food allergy diagnosis, there are various obstacles such as time, resources, and risk of severe reaction. Thus, identifying specific IgE (sIgE) levels predictive of OFC outcomes for individual tree nuts would be important to help guide clinical decisions.

In a recent article in The Journal of Allergy and Clinical Immunology: In Practice, Hsu et al performed a retrospective chart review in patients (0-20 years) who completed an unblinded OFC to any tree nut from 2007-2019 at Lurie Children’s Hospital of Chicago. They collected demographic data, personal and family history of atopy, details of previous reactions, and skin prick test results and sIgE levels at diagnosis and time of challenge to individual tree nuts. Almond, cashew, hazelnut, and walnut had sufficient data for statistical analysis. Differences among these four nuts were compared and probability curves were used to estimate positive predictive values (PPV) of sIgE at the time of OFC.

Overall, Hsu et al. analyzed over 500 tree nut OFCs and reported that differences exist among individual tree nuts. Most children pass almond and hazelnut OFCs even with sIgEs at OFC over the current suggested decision point threshold (5 kU/L). Pass rates for cashew and walnut were significantly lower (p<0.0003) and 50th percentile PPV for cashew and walnut were also lower than the commonly used 5 kU/L threshold (3.35 kU/L and 2.84 kU/L respectively). Additionally, the authors found that children who were avoiding tree nuts due to sensitization to one or more other nuts were more likely to tolerate the nut during OFC than those who had a prior ingestion and reaction. The results suggest that almond and hazelnut could be challenged more aggressively, and cashew and walnut challenged more conservatively.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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